An increasingly sensitive environmental issue is that of preventing injury to wildlife that may occur as a result of contact with energized electrical distribution components. Modernly, electrical distribution systems rarely provided any type of electrical barrier between energized components and other objects. For instance, electrical conductors that carry electrical power from power-pole to power-pole are typically devoid of any type of insulation. In the general sense, this is quite acceptable since electrical injury typically requires a complete circuit path phase to ground or phase to phase. Hence, a small bird may land on an electrical conductor without any adverse effects. This is because the small bird contacts only one electrical conductor and the current flowing through the conductor cannot find a “path to ground”.
It is only when a living creature, including man or beast, contacts an exposed electrical conductor or other energized component and electrical current can find a path to ground that severe injury can occur. This type of unfortunate incident is more likely to occur where exposed electrical conductors are in close proximity to a grounded object or to another conductor or component that is carrying an opposite phase of a particular circuit.
In one example, a conductor, which is typically electrically isolated from a power pole by means of an insulator, can be contacted by a lineman or wildlife that has climbed the power pole. Such an insulator is also known as an insulative support. In one case, a living creature is in close enough proximity to ground by virtue of being in contact with the power pole that the slightest contact with an exposed electrical conductor or other energized component may prove fatal. Larger birds, such as raptors, are often killed when they land on or attempt to land on an exposed electrical conductor near a power-pole or on the power-pole itself. When landing on the conductor near a power-pole, a larger bird can touch the power-pole with a wing and provide a path to ground. A large bird may also short two opposite phases together. This results in a short circuit where electrical current flows through the body of the unfortunate bird from one phase to the other.
Insulative supports are designed to isolate a power phase either from ground or from another phase included in an electrical power distribution system. It is not uncommon that such insulative supports support dielectric strengths greater than 60,000 volts. In order to achieve such high voltage isolation, many insulative supports are designed with one or more “skirts”. A skirt is a profile that elongates the dielectric distance of an insulator in an efficient manner and is more fully described infra.
It is in proximity to such an insulative support that many injuries occur. The need to avert such injuries has led to the development of a wide variety of covering means. For example, Tipsord describes in U.S. Pat. No. 2,871,282 an apparatus for covering a portion of a conductor proximate to an insulative support. The apparatus in Tipsord is clearly intended for short-term installation—perhaps during brief periods when a lineman is servicing the distribution system. According to Tipsord, a portion of a conductor proximate to an insulative support is covered together with the entire insulative support. This arrangement is unacceptable for long-term installations intended to help prevent injury to wildlife on a sustained basis. The reason for this is simple, by covering the entire insulative support, the dielectric integrity of the insulative support is compromised. The most notable means of such compromise is by shorting across one or more skirts included in an insulative support. One other problem associated with entirely covering an insulative support is that such covering precludes periodic maintenance of the insulative support. For example, an insulative support requires periodic cleaning because accumulation of particulate matter on the surface of a skirt also reduces its dielectric strength resulting in a compromise in dielectric integrity. This is because the particulate matter is typically a conductive substance.